It is narrated from Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with them both) that a Bedouin came to the Prophet (peace and blessings be upon him) and said: What is the "Trumpet" (sur, which will be blown on the Day of Resurrection)? He (peace and blessings be upon him) said: "It is a horn (-like instrument) into which a blowing will be made." This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.